How to Find Line Number of a Given Word in text file using Python?

In this article, we will show you how to find the line number where a specific word appears in a text file using Python. This is useful for searching keywords in documents, logs, or code files.

Let's assume we have a text file named TextFile.txt with the following content ?

Good Morning TutorialsPoint
This is TutorialsPoint sample File
Consisting of Specific
source codes in Python,Seaborn,Scala
Summary and Explanation
Welcome TutorialsPoint
Learn with a joy

Algorithm

Following are the steps to find line numbers containing a specific word ?

• Open the text file in read mode

• Initialize a line counter starting from 1

• Iterate through each line of the file

• Split each line into words and check if the target word exists

• Print the line number when the word is found

• Increment the line counter for each line processed

Method 1: Using split() and in Operator

This method splits each line into words and checks for exact word matches ?

# Create a sample text file first
with open("TextFile.txt", "w") as f:
    f.write("Good Morning TutorialsPoint\n")
    f.write("This is TutorialsPoint sample File\n")
    f.write("Consisting of Specific\n")
    f.write("source codes in Python,Seaborn,Scala\n")
    f.write("Summary and Explanation\n")
    f.write("Welcome TutorialsPoint\n")
    f.write("Learn with a joy\n")

# Find line numbers containing the word
target_word = "TutorialsPoint"
line_number = 1

print(f"The word '{target_word}' is present in the following lines:")

with open("TextFile.txt", "r") as file:
    for line in file:
        # Split the line into words
        words = line.split()
        
        # Check if target word exists in the words list
        if target_word in words:
            print(line_number)
        
        line_number += 1

The word 'TutorialsPoint' is present in the following lines:
1
2
6

Method 2: Using enumerate() for Cleaner Code

The enumerate() function automatically handles line numbering ?

target_word = "TutorialsPoint"
found_lines = []

with open("TextFile.txt", "r") as file:
    for line_num, line in enumerate(file, 1):
        if target_word in line.split():
            found_lines.append(line_num)

print(f"Word '{target_word}' found on lines: {found_lines}")

Word 'TutorialsPoint' found on lines: [1, 2, 6]

Method 3: Case-Insensitive Search

To make the search case-insensitive, convert both the line and target word to lowercase ?

target_word = "tutorialspoint"  # lowercase search term

with open("TextFile.txt", "r") as file:
    for line_num, line in enumerate(file, 1):
        # Convert to lowercase for case-insensitive comparison
        words = [word.lower() for word in line.split()]
        
        if target_word.lower() in words:
            print(f"Line {line_num}: {line.strip()}")

Line 1: Good Morning TutorialsPoint
Line 2: This is TutorialsPoint sample File
Line 6: Welcome TutorialsPoint

Method 4: Using a Function

Create a reusable function to find word occurrences ?

def find_word_lines(filename, word, case_sensitive=True):
    """
    Find line numbers containing a specific word.
    
    Args:
        filename: Path to the text file
        word: Word to search for
        case_sensitive: Whether to perform case-sensitive search
    
    Returns:
        List of line numbers where word is found
    """
    found_lines = []
    
    try:
        with open(filename, "r") as file:
            for line_num, line in enumerate(file, 1):
                words = line.split()
                
                if case_sensitive:
                    if word in words:
                        found_lines.append(line_num)
                else:
                    words_lower = [w.lower() for w in words]
                    if word.lower() in words_lower:
                        found_lines.append(line_num)
                        
    except FileNotFoundError:
        print(f"File '{filename}' not found!")
        return []
    
    return found_lines

# Test the function
result = find_word_lines("TextFile.txt", "TutorialsPoint")
print(f"Word found on lines: {result}")

# Case-insensitive search
result_case_insensitive = find_word_lines("TextFile.txt", "python", False)
print(f"Word 'python' found on lines: {result_case_insensitive}")

Word found on lines: [1, 2, 6]
Word 'python' found on lines: [4]

Comparison

Conclusion

Use the split() method with the in operator for exact word matching. For more flexible applications, implement case-insensitive search and wrap the logic in a reusable function with proper error handling.